Telescopic piston type lifting jack



Jan. 13, 1953 w p -rs TELESCQPIC PISTON TYPE LIFTING JACK 2 SHEETS- SHEET 1 Filed April 8, 1949 Patented Jan. 13, 1953 UNITED STATES rarest TELESCOPIC PISTON TYPE LIFTING JACK William E. Pitts, Bloomington, Ind. Application April 8, 1949, Serial No. 86,230

(Cl. l2146) Claims. 1

This invention relates to improvements in lifting jacks and more particularly to lifting jacks designed as permanently positioned units for the axles of motor vehicles and the like. For the purposes of illustration in the present specification, the use of the device for the changing of tires is hereinafter described, but it is to be understood that the invention is not limited to this particular field of service.

One object of the invention is to provide a permanently positioned unit carried by the axle assemblage in normally inactive or collapsed status but which is available for active service to raise the axle to the desired extent to permit removal and replacement of a wheel. The jack assembly may be a single unit for the axle, thus raising the entire axle, or the axle may have individual units for each wheel.

Another object of the invention is to provide a device formed of sections and capable of movement between nested and expanded positions, the nested position being that in which the structure is being carried in its inactive position on the vehicle, thus permitting the vehicle to travel with a reasonable road clearance, and, at the same time, when expanded, to meet any reasonable lifting requirement with respect to the axle, the sections being arranged telescopically and so formed as to be expanded by controlled fluid pressure.

To these and other ends, therefore, the nature of which will be more clearly explained as the invention is hereinafter disclosed, said invention consists in the improved constructions and combinations of parts hereinafter described, illustrated in the accompanying drawings, and more particularly pointed out in the appended claims.

In the accompanying drawings, similar reference characters indicate similar parts in each :of the views, and

Figure l is a side elevation of one of the lifting jacks shown in its inactive position;

Figure 2 is a vertical sectional view of the .same with the structure partially expanded;

Figure 3 is a sectional view taken on line 33 of Figure 2;

Figure 4 is a view, partly in section and partly in elevation, with the parts in their inactive position;

Figure 5 is a certain of the parts in a different position; and

Figure 6 is a view partly in elevation and partly in section, showing the assembly in its fully expanded position.

hi the present invention, designed particularly for operation by air pressure, the disclosure is restricted to the structure of the jack assembly per se, the details relative to the air supply being omitted, since this can be provided in many different ways. For the purpose of the disclosure, the air supply may be assumed to be from a storage supply, although, practice, the vehiview similar to Figure 2 with i 2 cle will carry means for developing the needed air pressures. In other Words, the disclosure refers to the structure of the jack assembly rather than to the particular medium through which it is operated. This is for the reason that the structure can be, with minorchanges, utilized with oil as the operating medium.

A jack assembly of the present invention must be formed of at least two sections telescopically arranged. In the specific service herein disclosed, at least three sections are essentialkdue to the fact that the space below the vehicle i is limited as to height from the traction surfac and the assembly must be capable of being nested into a compass which will leave a reasonable road clearance below. At the same time, the device must be capable of bridging such height as well as of providing additional expansion sufficient to raise the axle the distance reduired to permit the desired wheel changes.

In the drawings, the jack assembly, as an entirety, is indicated at it, with the sections indicated as H, l2 and 53, respectively. Of these sections, section I i is the outer section, 52 the inner section, and E3 the intermediate section. Each section is annular in form and relatively dimensioned as to permit proper nesting as presently described in detail and as indicated in Figure 4.

The section H is of a desired vertical length and has a, top Ila, the sidewall being circular in contour and of desired thickness. Top Ha carries a controllable port it, for air Supply under pressure, and a controllable port 15 for air exhaust purposes. The top also preferably carries one or more bleeding ports it, normally closed by a screw plug Ida, for permitting more rapid air discharge when rap-id nesting of the assembly is desired. At the bottom of the section i! there is formed externally an annular rib Hb designed to cooperate with latching members to hold the assembly in nested position, as presently described. The lower zone of section H is threaded internally. The wall of the threaded zone is of decreased thickness, as at Me, to receive an annular packing formation '3 formed in two parts with an intervening packing, the upper of such parts carrying an upwardly-extending annular shoulder i'la, the top of which is located above the plane of a'controllable side port is; the port I 8 is equipped with a three-way valve or its equivalent to permit its use for supply or exhaust service at will. If desired, additional ports Hid, normally closed by threaded plugs lfib, may be employed, these being positioned below the top plane of shoulder Ila. 1

.The intermediate section I3 is annular and of circular contour and with open top and bottom. Its external diameter is materially less than the internal diameter of section ll, thereby providing an annularspace or chamber l9 between'the' two sections above formation I l and to which port I8 is accessible, the inner face of the formation I! fitting the exterior wall of section I3 to permit sliding movement of the section relative to the formation but to prevent leakage of content from space I9 through the formation IT. The upper zone of the wall of section I3 is reduced in thickness to provide an external thread zone I3a. adapted to receive the members of an annular sliding flange 20, the external diameter of which closely fits the interior of section Ii. Section I3 is thus supported telescopically relative to section II and in axial alinement therewith, such sliding movements being active to vary the dimensions of space I9. However, the downward movement of section I3 is limited by contact of flange 20 with the top of shoulder Ila, leaving port I8 exposed to such space I9 in all positions of the section. The lower zone of section I3 is also of reduced thickness and provided with an internal thread zone I3b adapted to receive an annular packing formation 2 I, similar in type to formation I7, provided with upwardly extending shoulder 2Ia. The wall of section I3 is provided with two or more spaced ports 22 positioned below the top plane of shoulder 2Ia but above the top plane of shoulder Ila when section I3 is in nested position.

Section I2 is the inner section and it body is circular in contour and of materially less external diameter than the internal diameter of section I3, thereby forming a space or annular chamber 23 between the two sections. Section I2 includes a closed top I2a, preferably formed with a depressed zone I2b on its upper face. This top zone is provided with an external thread I20 to receive the members of an annular slidin flange 24 the exterior of which is adapted to have sliding contact with the interior of section I3. Since the exterior of the body of section I2 is also in sliding contact with the inner face of packin formation 2 I, it will be understood that section I2 is supported telescopically relative to section I3 and in axial alinement therewith, with the sliding movements of section I2 or I3 or of both sections active to vary the dimensions of space or chamber 23.

As indicated clearly in Figure 2, the lower end of section I2 is closed by bottom member I2d threadedly connected to the lower end of the section. Member I2d is formed with a projecting threaded boss I2e designed to carry and support the foot member 25, the latter being circular in contour and dimensioned to overlie rib I I?) when the jack is in its nested position as indicated in Figure 4. The periphery of member 25 carries spaced upwardly extending spring hooks 25 adapted to sna over the rib when the parts are in the position shown in Figure e, thus retaining the assembly inactive. If desired, the lower face of member 25 may be shaped as shown with a central boss 25a designed to normally provide the actual contact with the traction Surface when the assembly is in use. In Figures .5 and 6 the boss 25a is shown as supported on a block 36 which forms no part of the invention.

As will be understood from Figure 2, showing section I2 as completely closed, the section is a hollow section serving merely as the movable foot carrier and is subjected to air pressure during the expansion cycle-only at its top surface; during the nesting cycle the underside of the flange 24 of the section is subjected to air pressure within space 23 to raise the section. As presently described, the air pressure condit ons for sections II and I2 are somewhat different from those of section I3.

The assembly is mounted on the vehicle in any convenient manner, the drawings showing a bracket 35 secured to the exterior of section II, this being secured to the under side of a vehicle part 36 which may be part of an axle assembly, for instance. One of the assemblies may be carried in the mid zone of the length of each axle, or, if preferred, there may be an assembly for each wheel, thus placing the mounting in the vicinity of the end of the axle.

During normal vehicle use, the jack is in its in active nested condition, illustrated in Figures 1 and 4. In such position spaces I9 and 23 are filled with air, with ports I4, I55 and I8 closed. Since port I8 forms the only outlet from the spaces I9 and 23, it can be understood that the closed port I8 traps the air in these spaces, thus cushioning sections I2 and I3, thereby aiding the clips 26 in holding the jack in nested position.

Since, during the previous nesting cycle, the sections I3 and I2 were raised to nested position with their top marginal faces contacting the inner top face of section II by the filling of spaces I9 and 23 with air which was then trapped by the closure of port IS, the only portion of the top surface of the assembled sections I2 and I3 freely accessible for fluid-pressure supply through port I4 is the space I 2b in the top of section I2, the contacting marginal top faces of these sections preventing any material leakage of air beyond such depressed zone I21). Hence, when port I4 is opened for service, its pressure effect is limited to the top of section I2 without placing any material pressure on the top flange 2B of section I3. When, therefore, after hooks 26 are released, port I8 is opened in succession to port It, the pressure on the top of section I2 causes the latter to begin downward movement, its flange 24 forcing the previously trapped content from space 23 out through ports 22 into the outer space I9; inasmuch as ports 22, like port is, are in the lower zone of space I9, and top of section I2 is being subjected to the maximum pressure, with no material pressure being applied to the top of section I3, it will be understood that the supply of trapped air exhausted through port I8 is, in effect, being supplied from inner space 23 although actually reaching port I8 from space I9, port I8 controlling the rate of discharge and thus controlling the rate of downward travel of section I2; section I3 remains stationary during this downward travel since no material pressure is being applied to section I3 and space 23 is supplyin all the pressure taken by port IS, the major portion of the content of space I9 thus remaining within the space.

This condition will continue until the flange 24 of section I2 reaches and contacts flange ZIa of section I3, thereby completing the full length of the stroke of section I2, the latter being the only movable section during this period, and is made possible through the fact that ports 22 have not changed position during this period. As indicated in Fig. 2, this practically evacuates the space 23 from its trapped air content. The period constitutes the first stage of the expansion cycle.

Since the pressure supply through port I4 continues after contact of flanges 24 and 2Ia, sec tion I2 becomes a power source for drawing section I3 downward, with section I2 traveling with section I3. After the downward movement of section I3 begins, its flange 20 also i exposed to the pressure through port I I to aid in moving section is downward. The beginning of such downward movement of section I3 will carry ports 22 into the zone of flanges I1 and He of section I I, and while traveling through this flange zone, ports 22 will be closed off in the expanding cycle, such cut-off does not affect the operation, since inner space 23 is practically evacuated at such time. When, however, the downward travel of section I3 below such flanges exposes ports 22 below the flanges communication with the inner space 23 is reestablished but the communication is with the atmosphere and not the fluid pressure. Such communication is provided to permit the free expansion and contraction of the inner space 23 whenever needed in the further development of the cycle.

This downward travel of sections I3 and I2 together will continue until the foot 25a contacts the supporting surface, which may be the traction surface or the block 30, preventing further downward movement of the inner section I2, the pressure from port I4 however, continuing action on the closed top of the section, thus firmly holding it in position on the surface; this pressure also continues on flange 29 of section I 3, and since there is no restraint on the downward movement of the latter, this section continue to travel down until flange 29 seats on flange I'Ia of the outer section II; this flange contact remains constant during the remainder of the expansion cycle. This has the efiect of evacuating the outer space l9 of its trapped air, and ends the second stage of this cyclethe positions of the sections at such time is shown in Figure 5.

The third and final stage of the cycle is that of raising the vehicle and is produced by the continued application of pressure from port [4, port I8 being now preferably closed, since space I9 is evacuated and space 23 is in open communication with the atmosphere through ports 22. Such admitted pressure from port I4 raises section II, the latter drawing section l3 with it, due to the contacting flanges [1a and 20, the distance of raise being controlled by the operator who closes port l4 when the vehicle has reached the desired height; the maximum distance possible carries section I3 to the position shown in Fig. 6, but whatever the distance may be the vehicle weight is holding the expanded jack firmly to itssupporting surface through the trapped pressure within section I I and within the open top of section I3 and applied to the top of section I2, section I3 being held from rising from its seated position by the pressure on its flange 20.

The nesting cycle is likewise of three-stage type, the first stage being that Of lowering the vehicle until its wheels contact the traction surface, the action being produced by opening port I5, leaving ports l4 and I8 closed. This returns the sections to the positions of Fig. 5, with inner space 23 open to the atmosphere through ports 22 and ends this first stage of the nesting cycle.

The second stage of the nesting cycle is begun by opening port I8 with its pressure-supply formation active. This admits pressure to the evacuated outer space I9 causing flange 20 to rise and thus raise section I3, this rise continuing until the marginal top of the section contacts the inner face of the top wall of section I I, thus filling space I9 with pressure air and ending the second cycle. The movement of section l3 during the cycle is relative to section I2 as long as ports 22 remain below flange U, the content of space 23 exhausting through ports 22 during such period. However, when ports 22 pass into the zone v6 of the flange formation II-IIa, the ports 22 are temporarily closed by the formation, preventing further escape of content from space 23 until the ports emerge above flange II-a; while the ports are so closed, section I2 will move upward with section l3 for a distance equal to the depth of the flange formation.

The third and final stage of the nesting cycle is that of raising section I 2 to its nested position. and begins with the exposure of ports 22 above flange I'Ia, thus opening communication between the two spaces; since space I9 has been filled during the second cycle, the continued introduction of pressure into space I9 through port l8, causes the excess pressure to enter space 23 and become effective to raise flange 24, thus raising section l2, the raising movement continuing until the marginal top of section I2 contacts the top wall of section II, the fingers 23 being applied at the close of the stage.

As indicated by the above, the two cycles -expansion and nestingof the regimen controlling the jack operation in service are each composed of three stages which develop successively in each cycle. With the nested assembly having the spaces I9 and 23 filled with trapped fluid pressure, the regimen begins with the first stage of the expansion cycle, during which the content of the inner space 23 is evacuated, the inner section l2 being the sole movable section with the movement that of a complete stroke of the section. The second stage is purposed mainly to evacuate the trapped fluid pressureof the outer space I9 and incidently to open the inner space 23 to the atmosphere; both sections I2 and I3 travel together during a portion of the stage, after which section I 3 continues alone to complete its full stroke. The third stage is the raising of the vehicle, the outer and. intermediate sections II and I3 being movable together during the stage.

The nesting cycle presents as its first stage, the lowering of the vehiclewith the outer and intermediate sections movable together. The second stage is designed to restore the fluid pressure to the outer space I 9 and move section I3 to its nested position; section I3 moves alone during the greater portion of its stroke, section l2 traveling with it, during the period when ports 22 are passing the flanges I! and Ila; section I3 thus travels its complete stroke length. The third and final stage is designed to restore fluid pressure content to the inner space 23' and to position the inner section in its nested position; with the exception of the short distance it travels with section I3 during the second stage, the travel of the inner section I2 is of the length of its stroke-during the stage the section travels alone.

The stages of the two cycles are somewhat similar in type but in reverse order, the initial and final stages of the regimen dealing with the inner space 23 through the movement of the inner section l2 as the sole movable section during these stages; the middle stage of each cycle pertains moreparticularly to the outer space I9 and the free movement of atmosphere into and out of inner space'23-asection I3 travel alone and also together with section l2. The successive stages forming the final of the expansion cycle and the initial of the nesting cycle, pertain to the vehicle movement-the outer and intermediate sections travel together during these stages. There is'thus a systematic order chars acteristlc present throughout theregim'en' which reatly simplifies the jack operation, w

l The three sections disclosed will permit the assemblage o .be formed with an overall nested dimension such as to provide an adequate road clearance effect and at the same time assure ample expansion-especially the block 38 available- -so that the assemblage is sulnciently small in axial dimension as to provide efiicient service, and at the same time is so formed as to provide adequate strength and form for the purpose for which it is designed.

The jack is constructed of comparatively few parts with each having a form permitting of sturdy construction as well as ready production so that the cost of production is reasonably low a though it is very efiicient in service.

While I have herein shown and described a preferred form of the invention, it is apparent that changes or modifications therein may be found desirable or essential in meeting the exigencies of service or the desires of an individual user, and I therefore reserve the right to make any and all changes desirable or essential insofar as the same may fall within the spirit and scope of the invention as expressed in the accompanying claims when broadly construed.

What is claimed as new is:

l- The combination with a vehicle, of a lifting jack assemblage permanently mounted thereon, said assemblage comprising three coaxial sections relatively movable telescopically into and out of a nested relation with the outer section permanently positioned on the vehicle, said sections being in concentric spaced relation with the spacing provided by flanges carried by section end zones to form end closures for the respective spaces, opposite spacing members of a space being relatively movable by section telescoping movement to permit variation in volumetric space dimensions in the direction of the axis of the section telescoping movements, the lower zone of the 3 intermediate section above and in the vicinity of the spacing flange being perforated to permit communication between such spaces while the intermediate section is in nested position, the assemblage having the outer section as openbottoined, the intermediate section as open-ended both top and bottom and the inner section having a closed top and bottom, and controllable independent fluid pressure supply and exhaust means carried by the outer section, said means including a supply and an exhaust carried by the top in a mid-zone of the outer section and a fixture serviceable both :for exhaust and supply positioned inthe. lower zone of a side wall of such outer section, said assemblage having the top face of its inner section formed to annularly contact-engage the inner top face of the outer section beyond such mid-zone of the latter when the sections are in nested relation, the inner section top face-having a depressed mid-zone accessible to the fluid pressure supply in such nested relation, to there-,-

by restrict initial fiuid pressure activity solely to the closed top zone of the inner section, said assemblage having a service regimen consisting of a stage expanding cycle and astage nesting cycle with the sections in nested relation during service inactivity, said assemblage regimen being characterized in that the initial stage of the expanding cycle presents the inner section as the sole moving section of the assemblage with the movement extending throughout the individual stroke length of the section, the movement of said inner section in its nesting direction constituting the sole moving section during the final stage of the nesting cycle of the regimen with the movement extending substantially throughout the individual stroke lengthof the section.

2. ,An assemblage as in claim 1 characterized in that the position of the periorate zone .ofthe intermediate section issue-h as to permit approximately complete evacuation of the volumetric content of theinnerspace into the outer space during and by such initial stage movement of the imier section and en route to the assemblage exhaust and to concurrently maintain the intermediate section in its nested position during such stage.

3,. An assemblage as in claim 2 characterized in that the relative position of the spacing flanges on the inner and intermediate sections respectively is such that the close of the individual stroke length of the inner section at the end of the initial stage places said flanges in contact engagement to thereby constitute said inner section as apower source ,for drawing the intermediate section from its nested position and to thereby render the upper spacing flange ofsuch intermediate section subject to the assemblage 'fi-uid pressure to render both sections active to discharge content of the outer space and thereby produce the second stage of the expansion cycle and to place the lower end zone'of the inner section in its position for supportinr .theexpected load with the latter constituting the third stage of the expansion cycle, the load being produced by the upward movement of the outer section relative to the inner section with the intermediate section idly rising with the outer section.

4. An assemblage as in claim 3 characterized in that the position of the spacing flanges carried by the outer section relative to the position of the perforate zon of the intermediate section in nested position is such that while the intermediate section is in nested position the spacing flanges of the outer section form the lower bounds of the outer space with the perforate zone located above such outer section flange, the expending movement of the intermediate section being operative to carry its perforate zone below the outer section flange and to open communication with the atmosphere therebelow to thereby render the inner space freely variable as to volumetric dimensions produced by movements of the inner and intermediate sections relative to each ot er in opposite directions while such perforate zone is so exposed.

5. An assembla e as in claim 1 characterized in that the stage development of the nesting cycle is substantially the reverse in order to that of the expansion cycle, the directional" advanc of the inner and intermediate sections in one cycle be: ing reversed when the action is in the other. cycle.

WILLIAM E.,.PITTS.

REFERENCES-CITED The following references are of record in the file of this patentz UNITED STATES PATENTS Number Name Date 902,723 Gauer Nov. 3, 1908 1,130,884 Blakey et a1. Mar. 9, 1915 1,548,182 Burgin Aug; 3, 1925 1,731,254 McNab Oct. 15, 1929 1,780,972 Neuberg Nov. 11,1930 1,83%,295 Stevenson 1 Dec. 1, 1931 2,0 0, Perkins "4","--- Nov, 10, 1936 2,162,931 Bissell ',e JunII'ZO, L935 

